2 x PCIe 3.0 x16 slots (supports x16/x4 mode)*&nbsp,3 x PCIe 3.0 x1 slots**1 x PCI slot* The PCI_E4 slot will be unavailable when an M.2 PCIe SSD module has been installed in the M.2_2 slot.** The PCI_E2/ PCI_E5 slot will be unavailable when an expansion card has been installed in the PCI_E3/ PCI1 slot.